1. Field of the Invention
The present invention generally relates to card-type electronic devices, and particularly, to a card-type electronic device in which a circuit board for mounting parts such as an IC is provided.
A PC card is conventionally known as one type of card device. Recently, multi-function and increased function of PC cards as well as various parts mounted thereon have been achieved. Accordingly, the shape (width, height) of the parts mounted on the PC card has been varied, and, hence, there are demands for a mounting structure by which these parts can be efficiently accommodated in a PC card.
For this reason, when designing a structure of a card which mounts parts having various heights, a frame having an offset suitable for a height of a particular part is selected, taking into account a positional relationship between a center of the shape of a PC card and a center of a circuit board, combined with a suitable connector.
On the other hand, due to the various shapes of the mounting parts available these days, there are cases where the parts are mounted on both sides of a circuit board or a part having an increased height is mounted on a board. In such cases, it is necessary to change the board position (offset) in the PC card due to a height restriction of a mounting part.
In order to make such changes, it is necessary to produce or purchase a suitable frame and this increases the number of production lines and cost necessary for the frames. Also, extra time may be required for the development or production of PC cards.
Accordingly, it is necessary to reduce the cost of PC cards by decreasing the number of construction parts. This may be achieved by using a fewer number of frames without producing or purchasing new frames. Also, it is necessary to provide a PC card with a frame having a suitable offset structure so that a multi-function device may be mounted.
2. Description of the Related Art
FIGS. 1 through 5 are diagrams showing a conventional card-type electronic device. In FIGS. 1 through 5, a PC card is shown as an example of the card-type electronic device. FIG. 1 is a diagram showing an exploded view of a conventional PC card 1. FIG. 2 is a diagram showing a perspective view of the PC card 1.
As shown in FIGS. 1 and 2, the PC card 1 is comprised of an IC module 2, a frame 3, and a pair of metal panels 4 and 5. The IC module 2 has a structure in which a connector 6, a mounting part (an IC) 8, etc., are mounted,. using solder, on a printed wiring board (circuit board) 7. In the IC module 2, IC terminals of the IC 8 are electrically connected with connector terminals 10 of a connector 6 by being soft soldered onto the printed wiring board 7.
The frame 3 is generally formed of a plastic resin and includes a positioning portion 11 at the inner periphery thereof. The height position of the IC module 2 in the PC card 1 is determined when the printed wiring board 7 is engaged with the positioning portion 11 and the printed wiring board 7 is supported by the positioning portion 11.
The metal panels 4 and 5 may be formed of, for instance, SUS and are provided so as to sandwich the IC module 2.
In order to assemble the PC card 1 having the above structure, the pair of metal panels 4 and 5 are adhered to the frame 3 so as to sandwich the IC module 2 after the IC module 2 is located at the positioning portion 11 which is formed with the frame 3.
FIG. 3 is a diagram showing a structure of the conventional frame 3 in detail.
As mentioned above, the positioning portion 11 of the frame 3 supports the printed wiring board 7 and determines the height position (board offset) thereof. Also, the metal plates 4 and 5 are fixed to an upper surface 12 and a lower surface 13, respectively, of the frame 3. When the metal plates 4 and 5 are adhered to the frame 3, the mounting part (the IC) 8 is sealed therein by a mechanical engagement. Moreover, connector engaging portions 14 are provided with the frame 3, which support the connector 6 by being engaged with a corresponding convex portion 15 formed on the right-hand and left-hand sides of the connector 6, respectively.
In the positioning structure of the conventional printed wiring board 7, the positioning portion 11 for mounting the printed wiring board 7 is formed with the frame 3 and the printed wiring board 7 is mounted on the positioning portion 11. The offset position (i.e., the height position) of the printed wiring board 7 is determined by taking into account a productivity during construction, automation of the construction, and stabilization of mechanical strength of a product.
However, the position of the positioning portion 11 is conventionally formed at a single height of the frame 3. Therefore, if the offset position of the printed wiring board 7 is once determined, the height of the mounting part 8 which can be employed is automatically determined and use of a mounting part whose height is not within the allowable range is restricted.
In order to avoid the above problem, it may be possible not to use a positioning structure, or to change the shape of the metal plates 4 and 5 as shown in FIGS. 4 and 5.
However, if the positioning structure is not used, the printed wiring board 7 cannot be fixed and the productivity during construction may be decreased and the mechanical strength of the product may be lowered. Also, the shape of the metal plates 4 and 5 cannot be changed for a card-type electronic device such as a PC card whose size is already determined.
Accordingly, when a mounting part 8 which has a height greater than the allowable range is mounted using the frame 3, it is necessary to change the offset position, and in order to change the offset position, it is necessary to produce or purchase a new frame 3 which has an offset position altered accordingly.
Also, since the offset position is determined by the positioning portion 11 of the frame 3, selection of parts is restricted and a mounting part 8 having a height that is a little higher than the allowable range cannot be mounted. Likewise, when a mounting part 8 having a height that is lower than the allowable range is used, dead space is generated in the PC card and qualities thereof such as mechanical strength is reduced.
In order to avoid the above problems, it is necessary to produce a frame 3 having an offset position at a different portion. That is, one frame is necessary for one offset portion.